I dont have much to add, but I think Yokohama owns Yokohama tires and Advan wheels.
Here's a listing of sizes and offsets. I had to highlight the table to see the text...
http://www.hopupracing.com/admo6wh.html
I think Advan's a pretty good (popular) company. They make SUper Advans which people are crazy about. I really like the model 5. If you want a 6 spoke, also check out the RG II and the T6 (looks very similar to the model 6). Wheelweight.net didnt have the model 6 listed (they have the RG in many sizes), but wheelspecs.com did say they were cast.